Matsushita Electric Industrial Co., Ltd.

Masato Izawa

Kiyokazu Hashimoto

Masafumi Sato

Hiroshi Horikane

A playback clock extracting device having: a quantization member for quantizing, at a sampling clock rate having a rate twice a recording rate, a signal played back from a recording medium so as to output sample data, a digital equalizer for subjecting the sample data to digital equalization so as to alternately output playback data and PLL data at an interval of one sampling clock, cycle a ternary decision member for making a ternary decision as to whether the playback data is positive, zero or negative. The playback clock extracting device further having arithmetic unit for calculating a sampling phase error in the quantization member by multiplying a result of the decision of the ternary decision member by a difference between two successive data values of the PLL data outputted immediately prior to and immediately after the playback data for the decision of the ternary decision member, respectively, a sampling clock generating member which controls a phase and an oscillation frequency on the basis of the sampling phase error outputted by the arithmetic unit so as to generate the sampling clock, and a playback clock generating member which divides a frequency of the sampling clock by two so as to generate a playback clock for detecting the playback data.

Playback clock extracting apparatus

A digital recording and playback unit which prevents deterioration of reproduced video image due to confusion in servo control occurring at a chronologically discontinued portion in the recording at the time of playback when a wide head is used for reproducing assembled video data recorded in a narrow track width. The digital recording and playback unit include a decoding circuit for decoding the reproducing signal to digital playback data, an error correction circuit for restoring erroneous portions of the data decoded by the decoding circuit, a first frame memory used for making corrections by the error correction circuit, a deshuffling circuit for reassembling data restored by the error correction circuit, a second frame memory used for deshuffling by the deshuffling circuit, a detecting circuit for detecting a chronologically discontinued portion in the recording at the time of playback, and a control circuit for instructing writing and reading to and from the first and second frame memories based on the output of the detecting circuit. Helical scanning is employed and one frame of the video image consisting of multiple tracks is recorded in a track width of 2 W/3, where W is the width of a recording and playback head.

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Neyagawa, Japan

Masato Izawa